1. Technical Field
The invention relates to a fluid ejection device for applying a drive signal to an actuator to thereby eject a fluid. The present invention is suitable for a fluid ejecting recording device adapted to print predetermined characters and images by ejecting microscopic droplets of fluids from nozzles of a fluid ejection head to form microscopic particles (dots) thereof on a print medium.
2. Related Art
Compared to an analog power amplifier for linearly driving a transistor pair push-pull-coupled to each other, a digital power amplifier (also often referred to as a class D amplifier) which switch-operates and power-amplifies switching elements push-pull-coupled is superior in efficiency, and is used in a wide range. In the case of using the digital power amplifier to, for example, output a drive signal to an actuator for ejecting a fluid from a nozzle of a fluid ejecting recording device, a modulator pulse-modulates a drive waveform signal forming the basis of the drive signal into a modulated signal, the digital power amplifier power-amplifies the modulated signal, a low pass filter filters the power-amplified modulated signal thus amplified, and then the resulting modulated signal is output as a drive signal. The low pass filter attenuates the frequency component of the pulse modulation. On this occasion, when the number of actuators to be driven is changed, the frequency characteristic of the filter composed of the low pass filter and the capacitance of the actuator varies, thus there might occur the case in which a desired drive signal fails to be obtained. Therefore, the inventor has provided an inverse filter, which is capable of obtaining a desired drive signal irrespective of the number of actuators to be driven, on the anterior stage of the modulator as described in international publication WO2007/083669.
However, in the fluid ejection device described in the document mentioned above, a plurality of inverse filters with transmission characteristics different from each other are provided and arranged in such a way that the inverse filters with different transmission characteristics are switched according to a number of actuators to be driven. Hence the corresponding number of circuits to the number of inverse filters are required, and therefore, the circuit size of the inverse filters becomes large.